The invention relates to an at least double-layer absorbent body for hygiene articles, specifically for sanitary napkins or panty liners, having a fluid absorption and distribution layer facing the body made of a first fibrous material with a first pore size and a fluid storage layer facing away from the body with a second pore size.
An absorbent body structure of this type is known from a plurality of publications, for example, EP 0 512 010 B1. In the case of this known absorbent body, the fluid absorption and distribution layer facing the body is formed from intra-linked cellulose fibers, known as curled-fiber material, which, even in its saturated state, retains a high pore volume and therefore promotes the rapid uptake of large quantities of fluid without capillary interstices becoming blocked and causing the impinging fluid to run off to the sides. In this curled-fiber material, the fibers are stiffened by hydrogen-bridge bonds formed inside a cellulose fiber, and the fibrous material tends, with suitable pre-compression, to expand in a saturated state, i.e., to increase in volume. Other fibrous materials which are suitable for the fluid absorption and distribution layer facing away from the body are thermally welded thermoplastic bi-component fibers which, as a result of the thermal welding, do not tend to collapse when impinged upon by fluid.
The task of the fluid absorption and distribution layer facing the body is to absorb impinging fluid, to hold it temporarily and distribute it within the layer, and then to release it to a storage layer lying thereunder which has a smaller pore size and thus higher capillarity. The greater the pore size of a fibrous layer, the less its capacity to transport fluid within the layer on the basis of capillary mechanisms, i.e., the lower the capillarity of this layer and vice-versa. Because of the small capillary fiber interstices in the storage layer, the fluid is transported to still unused areas of the absorbent body as the result of capillary fluid transportation within the storage layer. This transportation process requires a certain time, for which reason rapidly absorbing fluid absorption and distribution layers of the previously described type are used.
The layers used here are intended to be bonded to each other in a suitable way to simplify the handling of large panels of web material, but also to prevent slippage of the layers against each other when a hygiene article is used. To this end, a plurality of methods and means are known, as for example, the use of pressure-sensitive adhesives, thermal bonding of fibrous webs with the addition of thermoplastic fiber materials or of adhesive materials or the application of weld joints. Further, the bonding of large panels of web material by calendaring is known at least in principle as a measure to the person skilled in the art, although a possibly unintentional compression of the web material may result.
From EP 1 032 342 B1 it is known for example, for the adhesive-free production of a fibrous material web consisting of cellulose fibers, starting with an air-laid cellulose fibrous nonwoven, to take this nonwoven through the gap of a pair of calendaring rollers, where the pair of calendaring rollers has punctiform elevations which can be positioned opposite each other to almost touch and produce embossing points on both sides in the nonwoven and thus bond the nonwoven.